InterfaceUtils.hxx

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// Author: Enrico Guiraud, Danilo Piparo CERN  02/2018
 
/*************************************************************************
 * Copyright (C) 1995-2018, Rene Brun and Fons Rademakers.               *
 * All rights reserved.                                                  *
 *                                                                       *
 * For the licensing terms see $ROOTSYS/LICENSE.                         *
 * For the list of contributors see $ROOTSYS/README/CREDITS.             *
 *************************************************************************/
 
#ifndef ROOT_RDF_TINTERFACE_UTILS
#define ROOT_RDF_TINTERFACE_UTILS
 
#include <ROOT/RDF/RAction.hxx>
#include <ROOT/RDF/ActionHelpers.hxx> // for BuildAction
#include <ROOT/RDF/RBookedDefines.hxx>
#include <ROOT/RDF/RDefine.hxx>
#include <ROOT/RDF/RFilter.hxx>
#include <ROOT/RDF/Utils.hxx>
#include <ROOT/RIntegerSequence.hxx>
#include <ROOT/RDF/RJittedAction.hxx>
#include <ROOT/RDF/RJittedDefine.hxx>
#include <ROOT/RDF/RJittedFilter.hxx>
#include <ROOT/RDF/RLoopManager.hxx>
#include <ROOT/RMakeUnique.hxx>
#include <ROOT/RStringView.hxx>
#include <ROOT/TypeTraits.hxx>
#include <TError.h> // gErrorIgnoreLevel
#include <TH1.h>
 
#include <deque>
#include <functional>
#include <map>
#include <memory>
#include <string>
#include <type_traits>
#include <typeinfo>
#include <vector>
#include <unordered_map>
 
class TObjArray;
class TTree;
namespace ROOT {
namespace Detail {
namespace RDF {
class RNodeBase;
}
}
namespace RDF {
template <typename T>
class RResultPtr;
template<typename T, typename V>
class RInterface;
using RNode = RInterface<::ROOT::Detail::RDF::RNodeBase, void>;
class RDataSource;
} // namespace RDF
 
} // namespace ROOT
 
/// \cond HIDDEN_SYMBOLS
 
namespace ROOT {
namespace Internal {
namespace RDF {
using namespace ROOT::Detail::RDF;
using namespace ROOT::RDF;
namespace TTraits = ROOT::TypeTraits;
namespace RDFInternal = ROOT::Internal::RDF;
 
ColumnNames_t GetTopLevelBranchNames(TTree &t);
 
using HeadNode_t = ::ROOT::RDF::RResultPtr<RInterface<RLoopManager, void>>;
HeadNode_t CreateSnapshotRDF(const ColumnNames_t &validCols,
                            std::string_view treeName,
                            std::string_view fileName,
                            bool isLazy,
                            RLoopManager &loopManager,
                            std::unique_ptr<RDFInternal::RActionBase> actionPtr);
 
std::string DemangleTypeIdName(const std::type_info &typeInfo);
 
ColumnNames_t
ConvertRegexToColumns(const ColumnNames_t &colNames, std::string_view columnNameRegexp, std::string_view callerName);
 
/// An helper object that sets and resets gErrorIgnoreLevel via RAII.
class RIgnoreErrorLevelRAII {
private:
   int fCurIgnoreErrorLevel = gErrorIgnoreLevel;
 
public:
   RIgnoreErrorLevelRAII(int errorIgnoreLevel) { gErrorIgnoreLevel = errorIgnoreLevel; }
   RIgnoreErrorLevelRAII() { gErrorIgnoreLevel = fCurIgnoreErrorLevel; }
};
 
/****** BuildAction overloads *******/
 
// clang-format off
/// This namespace defines types to be used for tag dispatching in RInterface.
namespace ActionTags {
struct Histo1D{};
struct Histo2D{};
struct Histo3D{};
struct Graph{};
struct Profile1D{};
struct Profile2D{};
struct Min{};
struct Max{};
struct Sum{};
struct Mean{};
struct Fill{};
struct StdDev{};
struct Display{};
}
// clang-format on
 
template <typename T, bool ISV6HISTO = std::is_base_of<TH1, T>::value>
struct HistoUtils {
   static void SetCanExtendAllAxes(T &h) { h.SetCanExtend(::TH1::kAllAxes); }
   static bool HasAxisLimits(T &h)
   {
      auto xaxis = h.GetXaxis();
      return !(xaxis->GetXmin() == 0. && xaxis->GetXmax() == 0.);
   }
};
 
template <typename T>
struct HistoUtils<T, false> {
   static void SetCanExtendAllAxes(T &) {}
   static bool HasAxisLimits(T &) { return true; }
};
 
// Generic filling (covers Histo2D, Histo3D, Profile1D and Profile2D actions, with and without weights)
template <typename... ColTypes, typename ActionTag, typename ActionResultType, typename PrevNodeType>
std::unique_ptr<RActionBase>
BuildAction(const ColumnNames_t &bl, const std::shared_ptr<ActionResultType> &h, const unsigned int nSlots,
            std::shared_ptr<PrevNodeType> prevNode, ActionTag, const RDFInternal::RBookedDefines &defines)
{
   using Helper_t = FillParHelper<ActionResultType>;
   using Action_t = RAction<Helper_t, PrevNodeType, TTraits::TypeList<ColTypes...>>;
   return std::make_unique<Action_t>(Helper_t(h, nSlots), bl, std::move(prevNode), std::move(defines));
}
 
// Histo1D filling (must handle the special case of distinguishing FillParHelper and FillHelper
template <typename... ColTypes, typename PrevNodeType>
std::unique_ptr<RActionBase> BuildAction(const ColumnNames_t &bl, const std::shared_ptr<::TH1D> &h,
                                         const unsigned int nSlots, std::shared_ptr<PrevNodeType> prevNode,
                                         ActionTags::Histo1D, const RDFInternal::RBookedDefines &defines)
{
   auto hasAxisLimits = HistoUtils<::TH1D>::HasAxisLimits(*h);
 
   if (hasAxisLimits) {
      using Helper_t = FillParHelper<::TH1D>;
      using Action_t = RAction<Helper_t, PrevNodeType, TTraits::TypeList<ColTypes...>>;
      return std::make_unique<Action_t>(Helper_t(h, nSlots), bl, std::move(prevNode), std::move(defines));
   } else {
      using Helper_t = FillHelper;
      using Action_t = RAction<Helper_t, PrevNodeType, TTraits::TypeList<ColTypes...>>;
      return std::make_unique<Action_t>(Helper_t(h, nSlots), bl, std::move(prevNode), std::move(defines));
   }
}
 
template <typename... ColTypes, typename PrevNodeType>
std::unique_ptr<RActionBase> BuildAction(const ColumnNames_t &bl, const std::shared_ptr<TGraph> &g,
                                         const unsigned int nSlots, std::shared_ptr<PrevNodeType> prevNode,
                                         ActionTags::Graph, const RDFInternal::RBookedDefines &defines)
{
   using Helper_t = FillTGraphHelper;
   using Action_t = RAction<Helper_t, PrevNodeType, TTraits::TypeList<ColTypes...>>;
   return std::make_unique<Action_t>(Helper_t(g, nSlots), bl, std::move(prevNode), std::move(defines));
}
 
// Min action
template <typename ColType, typename PrevNodeType, typename ActionResultType>
std::unique_ptr<RActionBase> BuildAction(const ColumnNames_t &bl, const std::shared_ptr<ActionResultType> &minV,
                                         const unsigned int nSlots, std::shared_ptr<PrevNodeType> prevNode,
                                         ActionTags::Min, const RDFInternal::RBookedDefines &defines)
{
   using Helper_t = MinHelper<ActionResultType>;
   using Action_t = RAction<Helper_t, PrevNodeType, TTraits::TypeList<ColType>>;
   return std::make_unique<Action_t>(Helper_t(minV, nSlots), bl, std::move(prevNode), std::move(defines));
}
 
// Max action
template <typename ColType, typename PrevNodeType, typename ActionResultType>
std::unique_ptr<RActionBase> BuildAction(const ColumnNames_t &bl, const std::shared_ptr<ActionResultType> &maxV,
                                         const unsigned int nSlots, std::shared_ptr<PrevNodeType> prevNode,
                                         ActionTags::Max, const RDFInternal::RBookedDefines &defines)
{
   using Helper_t = MaxHelper<ActionResultType>;
   using Action_t = RAction<Helper_t, PrevNodeType, TTraits::TypeList<ColType>>;
   return std::make_unique<Action_t>(Helper_t(maxV, nSlots), bl, std::move(prevNode), std::move(defines));
}
 
// Sum action
template <typename ColType, typename PrevNodeType, typename ActionResultType>
std::unique_ptr<RActionBase> BuildAction(const ColumnNames_t &bl, const std::shared_ptr<ActionResultType> &sumV,
                                         const unsigned int nSlots, std::shared_ptr<PrevNodeType> prevNode,
                                         ActionTags::Sum, const RDFInternal::RBookedDefines &defines)
{
   using Helper_t = SumHelper<ActionResultType>;
   using Action_t = RAction<Helper_t, PrevNodeType, TTraits::TypeList<ColType>>;
   return std::make_unique<Action_t>(Helper_t(sumV, nSlots), bl, std::move(prevNode), std::move(defines));
}
 
// Mean action
template <typename ColType, typename PrevNodeType>
std::unique_ptr<RActionBase> BuildAction(const ColumnNames_t &bl, const std::shared_ptr<double> &meanV,
                                         const unsigned int nSlots, std::shared_ptr<PrevNodeType> prevNode,
                                         ActionTags::Mean, const RDFInternal::RBookedDefines &defines)
{
   using Helper_t = MeanHelper;
   using Action_t = RAction<Helper_t, PrevNodeType, TTraits::TypeList<ColType>>;
   return std::make_unique<Action_t>(Helper_t(meanV, nSlots), bl, std::move(prevNode), std::move(defines));
}
 
// Standard Deviation action
template <typename ColType, typename PrevNodeType>
std::unique_ptr<RActionBase> BuildAction(const ColumnNames_t &bl, const std::shared_ptr<double> &stdDeviationV,
                                         const unsigned int nSlots, std::shared_ptr<PrevNodeType> prevNode,
                                         ActionTags::StdDev, const RDFInternal::RBookedDefines &defines)
{
   using Helper_t = StdDevHelper;
   using Action_t = RAction<Helper_t, PrevNodeType, TTraits::TypeList<ColType>>;
   return std::make_unique<Action_t>(Helper_t(stdDeviationV, nSlots), bl, prevNode, std::move(defines));
}
 
// Display action
template <typename... ColTypes, typename PrevNodeType>
std::unique_ptr<RActionBase> BuildAction(const ColumnNames_t &bl, const std::shared_ptr<RDisplay> &d,
                                         const unsigned int, std::shared_ptr<PrevNodeType> prevNode,
                                         ActionTags::Display, const RDFInternal::RBookedDefines &defines)
{
   using Helper_t = DisplayHelper<PrevNodeType>;
   using Action_t = RAction<Helper_t, PrevNodeType, TTraits::TypeList<ColTypes...>>;
   return std::make_unique<Action_t>(Helper_t(d, prevNode), bl, prevNode, std::move(defines));
}
 
/****** end BuildAndBook ******/
 
template <typename Filter>
void CheckFilter(Filter &)
{
   using FilterRet_t = typename RDF::CallableTraits<Filter>::ret_type;
   static_assert(std::is_convertible<FilterRet_t, bool>::value,
                 "filter expression returns a type that is not convertible to bool");
}
 
void CheckDefine(std::string_view definedCol, TTree *treePtr, const ColumnNames_t &customCols,
                       const std::map<std::string, std::string> &aliasMap, const ColumnNames_t &dataSourceColumns);
 
std::string PrettyPrintAddr(const void *const addr);
 
void BookFilterJit(const std::shared_ptr<RJittedFilter> &jittedFilter, std::shared_ptr<RNodeBase> *prevNodeOnHeap,
                   std::string_view name, std::string_view expression,
                   const std::map<std::string, std::string> &aliasMap, const ColumnNames_t &branches,
                   const RDFInternal::RBookedDefines &customCols, TTree *tree, RDataSource *ds);
 
std::shared_ptr<RJittedDefine> BookDefineJit(std::string_view name, std::string_view expression, RLoopManager &lm,
                                                   RDataSource *ds, const RDFInternal::RBookedDefines &customCols,
                                                   const ColumnNames_t &branches,
                                                   std::shared_ptr<RNodeBase> *prevNodeOnHeap);
 
std::string JitBuildAction(const ColumnNames_t &bl, std::shared_ptr<RDFDetail::RNodeBase> *prevNode,
                           const std::type_info &art, const std::type_info &at, void *rOnHeap, TTree *tree,
                           const unsigned int nSlots, const RDFInternal::RBookedDefines &defines,
                           RDataSource *ds, std::weak_ptr<RJittedAction> *jittedActionOnHeap);
 
// Allocate a weak_ptr on the heap, return a pointer to it. The user is responsible for deleting this weak_ptr.
// This function is meant to be used by RInterface's methods that book code for jitting.
// The problem it solves is that we generate code to be lazily jitted with the addresses of certain objects in them,
// and we need to check those objects are still alive when the generated code is finally jitted and executed.
// So we pass addresses to weak_ptrs allocated on the heap to the jitted code, which is then responsible for
// the deletion of the weak_ptr object.
template <typename T>
std::weak_ptr<T> *MakeWeakOnHeap(const std::shared_ptr<T> &shPtr)
{
   return new std::weak_ptr<T>(shPtr);
}
 
// Same as MakeWeakOnHeap, but create a shared_ptr that makes sure the object is definitely kept alive.
template <typename T>
std::shared_ptr<T> *MakeSharedOnHeap(const std::shared_ptr<T> &shPtr)
{
   return new std::shared_ptr<T>(shPtr);
}
 
bool AtLeastOneEmptyString(const std::vector<std::string_view> strings);
 
/// Take a shared_ptr<AnyNodeType> and return a shared_ptr<RNodeBase>.
/// This works for RLoopManager nodes as well as filters and ranges.
std::shared_ptr<RNodeBase> UpcastNode(std::shared_ptr<RNodeBase> ptr);
 
ColumnNames_t GetValidatedColumnNames(RLoopManager &lm, const unsigned int nColumns, const ColumnNames_t &columns,
                                      const ColumnNames_t &validDefines, RDataSource *ds);
 
std::vector<std::string> GetValidatedArgTypes(const ColumnNames_t &colNames, const RBookedDefines &defines,
                                              TTree *tree, RDataSource *ds, const std::string &context,
                                              bool vector2rvec);
 
std::vector<bool> FindUndefinedDSColumns(const ColumnNames_t &requestedCols, const ColumnNames_t &definedDSCols);
 
using ROOT::Detail::RDF::ColumnNames_t;
 
template <typename T>
void AddDSColumnsHelper(const std::string &colName, RLoopManager &lm, RDataSource &ds)
{
   if (!ds.HasColumn(colName) || lm.HasDSValuePtrs(colName))
      return;
 
   const auto valuePtrs = ds.GetColumnReaders<T>(colName);
   std::vector<void*> typeErasedValuePtrs(valuePtrs.begin(), valuePtrs.end());
   lm.AddDSValuePtrs(colName, std::move(typeErasedValuePtrs));
}
 
/// Take list of column names that must be defined, current map of custom columns, current list of defined column names,
/// and return a new map of custom columns (with the new datasource columns added to it)
template <typename... ColumnTypes>
void AddDSColumns(const std::vector<std::string> &requiredCols, RLoopManager &lm, RDataSource &ds,
                  TTraits::TypeList<ColumnTypes...>)
{
   // hack to expand a template parameter pack without c++17 fold expressions.
   using expander = int[];
   int i = 0;
   (void)expander{(AddDSColumnsHelper<ColumnTypes>(requiredCols[i], lm, ds), ++i)..., 0};
}
 
// this function is meant to be called by the jitted code generated by BookFilterJit
template <typename F, typename PrevNode>
void JitFilterHelper(F &&f, const ColumnNames_t &cols, std::string_view name,
                     std::weak_ptr<RJittedFilter> *wkJittedFilter, std::shared_ptr<PrevNode> *prevNodeOnHeap,
                     RDFInternal::RBookedDefines *defines)
{
   if (wkJittedFilter->expired()) {
      // The branch of the computation graph that needed this jitted code went out of scope between the type
      // jitting was booked and the time jitting actually happened. Nothing to do other than cleaning up.
      delete wkJittedFilter;
      // defines must be deleted before prevNodeOnHeap because their dtor needs the RLoopManager to be alive
      // and prevNodeOnHeap is what keeps it alive if the rest of the computation graph is already out of scope
      delete defines;
      delete prevNodeOnHeap;
      return;
   }
 
   const auto jittedFilter = wkJittedFilter->lock();
 
   // mock Filter logic -- validity checks and Define-ition of RDataSource columns
   using Callable_t = typename std::decay<F>::type;
   using F_t = RFilter<Callable_t, PrevNode>;
   using ColTypes_t = typename TTraits::CallableTraits<Callable_t>::arg_types;
   constexpr auto nColumns = ColTypes_t::list_size;
   RDFInternal::CheckFilter(f);
 
   auto &lm = *jittedFilter->GetLoopManagerUnchecked(); // RLoopManager must exist at this time
   auto ds = lm.GetDataSource();
 
   if (ds != nullptr)
      RDFInternal::AddDSColumns(cols, lm, *ds, ColTypes_t());
 
   jittedFilter->SetFilter(
      std::unique_ptr<RFilterBase>(new F_t(std::forward<F>(f), cols, *prevNodeOnHeap, *defines, name)));
   // defines points to the columns structure in the heap, created before the jitted call so that the jitter can
   // share data after it has lazily compiled the code. Here the data has been used and the memory can be freed.
   delete defines;
   delete prevNodeOnHeap;
   delete wkJittedFilter;
}
 
template <typename F>
void JitDefineHelper(F &&f, const ColumnNames_t &cols, std::string_view name, RLoopManager *lm,
                     std::weak_ptr<RJittedDefine> *wkJittedDefine,
                     RDFInternal::RBookedDefines *defines, std::shared_ptr<RNodeBase> *prevNodeOnHeap)
{
   if (wkJittedDefine->expired()) {
      // The branch of the computation graph that needed this jitted code went out of scope between the type
      // jitting was booked and the time jitting actually happened. Nothing to do other than cleaning up.
      delete wkJittedDefine;
      // defines must be deleted before prevNodeOnHeap because their dtor needs the RLoopManager to be alive
      // and prevNodeOnHeap is what keeps it alive if the rest of the computation graph is already out of scope
      delete defines;
      delete prevNodeOnHeap;
      return;
   }
 
   auto jittedDefine = wkJittedDefine->lock();
 
   using Callable_t = typename std::decay<F>::type;
   using NewCol_t = RDefine<Callable_t, CustomColExtraArgs::None>;
   using ColTypes_t = typename TTraits::CallableTraits<Callable_t>::arg_types;
   constexpr auto nColumns = ColTypes_t::list_size;
 
   auto ds = lm->GetDataSource();
   if (ds != nullptr)
      RDFInternal::AddDSColumns(cols, *lm, *ds, ColTypes_t());
 
   // will never actually be used (trumped by jittedDefine->GetTypeName()), but we set it to something meaningful
   // to help devs debugging
   const auto dummyType = "jittedCol_t";
   // use unique_ptr<RDefineBase> instead of make_unique<NewCol_t> to reduce jit/compile-times
   jittedDefine->SetDefine(std::unique_ptr<RDefineBase>(
      new NewCol_t(name, dummyType, std::forward<F>(f), cols, lm->GetNSlots(), *defines, lm->GetDSValuePtrs())));
 
   // defines points to the columns structure in the heap, created before the jitted call so that the jitter can
   // share data after it has lazily compiled the code. Here the data has been used and the memory can be freed.
   delete defines;
   // prevNodeOnHeap only serves the purpose of keeping the RLoopManager alive so it can be accessed by
   // defines' destructor in case the rest of the computation graph is gone. Can be safely deleted here.
   delete prevNodeOnHeap;
   delete wkJittedDefine;
}
 
/// Convenience function invoked by jitted code to build action nodes at runtime
template <typename ActionTag, typename... ColTypes, typename PrevNodeType, typename ActionResultType>
void CallBuildAction(std::shared_ptr<PrevNodeType> *prevNodeOnHeap, const ColumnNames_t &cols,
                     const unsigned int nSlots, std::weak_ptr<ActionResultType> *wkROnHeap,
                     std::weak_ptr<RJittedAction> *wkJittedActionOnHeap,
                     RDFInternal::RBookedDefines *defines)
{
   if (wkROnHeap->expired()) {
      delete wkROnHeap;
      delete wkJittedActionOnHeap;
      // defines must be deleted before prevNodeOnHeap because their dtor needs the RLoopManager to be alive
      // and prevNodeOnHeap is what keeps it alive if the rest of the computation graph is already out of scope
      delete defines;
      delete prevNodeOnHeap;
      return;
   }
 
   const auto rOnHeap = wkROnHeap->lock();
   auto jittedActionOnHeap = wkJittedActionOnHeap->lock();
 
   // if we are here it means we are jitting, if we are jitting the loop manager must be alive
   auto &prevNodePtr = *prevNodeOnHeap;
   auto &loopManager = *prevNodePtr->GetLoopManagerUnchecked();
   using ColTypes_t = TypeList<ColTypes...>;
   constexpr auto nColumns = ColTypes_t::list_size;
   auto ds = loopManager.GetDataSource();
   if (ds != nullptr)
      RDFInternal::AddDSColumns(cols, loopManager, *ds, ColTypes_t());
 
   auto actionPtr = BuildAction<ColTypes...>(cols, std::move(rOnHeap), nSlots, std::move(prevNodePtr), ActionTag{},
                                                *defines);
   jittedActionOnHeap->SetAction(std::move(actionPtr));
 
   // defines points to the columns structure in the heap, created before the jitted call so that the jitter can
   // share data after it has lazily compiled the code. Here the data has been used and the memory can be freed.
   delete defines;
 
   delete wkROnHeap;
   delete prevNodeOnHeap;
   delete wkJittedActionOnHeap;
}
 
/// The contained `type` alias is `double` if `T == RInferredType`, `U` if `T == std::container<U>`, `T` otherwise.
template <typename T, bool Container = RDFInternal::IsDataContainer<T>::value && !std::is_same<T, std::string>::value>
struct RMinReturnType {
   using type = T;
};
 
template <>
struct RMinReturnType<RInferredType, false> {
   using type = double;
};
 
template <typename T>
struct RMinReturnType<T, true> {
   using type = TTraits::TakeFirstParameter_t<T>;
};
 
// return wrapper around f that prepends an `unsigned int slot` parameter
template <typename R, typename F, typename... Args>
std::function<R(unsigned int, Args...)> AddSlotParameter(F &f, TypeList<Args...>)
{
   return [f](unsigned int, Args... a) -> R { return f(a...); };
}
 
template <typename ColType, typename... Rest>
struct RNeedJitting {
   static constexpr bool value = RNeedJitting<Rest...>::value;
};
 
template <typename... Rest>
struct RNeedJitting<RInferredType, Rest...> {
   static constexpr bool value = true;
};
 
template <typename T>
struct RNeedJitting<T> {
   static constexpr bool value = false;
};
 
template <>
struct RNeedJitting<RInferredType> {
   static constexpr bool value = true;
};
 
///////////////////////////////////////////////////////////////////////////////
/// Check preconditions for RInterface::Aggregate:
/// - the aggregator callable must have signature `U(U,T)` or `void(U&,T)`.
/// - the merge callable must have signature `U(U,U)` or `void(std::vector<U>&)`
template <typename R, typename Merge, typename U, typename T, typename decayedU = typename std::decay<U>::type,
          typename mergeArgsNoDecay_t = typename CallableTraits<Merge>::arg_types_nodecay,
          typename mergeArgs_t = typename CallableTraits<Merge>::arg_types,
          typename mergeRet_t = typename CallableTraits<Merge>::ret_type>
void CheckAggregate(TypeList<U, T>)
{
   constexpr bool isAggregatorOk =
      (std::is_same<R, decayedU>::value) || (std::is_same<R, void>::value && std::is_lvalue_reference<U>::value);
   static_assert(isAggregatorOk, "aggregator function must have signature `U(U,T)` or `void(U&,T)`");
   constexpr bool isMergeOk =
      (std::is_same<TypeList<decayedU, decayedU>, mergeArgs_t>::value && std::is_same<decayedU, mergeRet_t>::value) ||
      (std::is_same<TypeList<std::vector<decayedU> &>, mergeArgsNoDecay_t>::value &&
       std::is_same<void, mergeRet_t>::value);
   static_assert(isMergeOk, "merge function must have signature `U(U,U)` or `void(std::vector<U>&)`");
}
 
///////////////////////////////////////////////////////////////////////////////
/// This overload of CheckAggregate is called when the aggregator takes more than two arguments
template <typename R, typename T>
void CheckAggregate(T)
{
   static_assert(sizeof(T) == 0, "aggregator function must take exactly two arguments");
}
 
///////////////////////////////////////////////////////////////////////////////
/// Check as many template parameters were passed as the number of column names, throw if this is not the case.
void CheckTypesAndPars(unsigned int nTemplateParams, unsigned int nColumnNames);
 
/// Return local BranchNames or default BranchNames according to which one should be used
const ColumnNames_t SelectColumns(unsigned int nArgs, const ColumnNames_t &bl, const ColumnNames_t &defBl);
 
/// Check whether column names refer to a valid branch of a TTree or have been `Define`d. Return invalid column names.
ColumnNames_t FindUnknownColumns(const ColumnNames_t &requiredCols, const ColumnNames_t &datasetColumns,
                                 const ColumnNames_t &definedCols, const ColumnNames_t &dataSourceColumns);
 
/// Returns the list of Filters defined in the whole graph
std::vector<std::string> GetFilterNames(const std::shared_ptr<RLoopManager> &loopManager);
 
/// Returns the list of Filters defined in the branch
template <typename NodeType>
std::vector<std::string> GetFilterNames(const std::shared_ptr<NodeType> &node)
{
   std::vector<std::string> filterNames;
   node->AddFilterName(filterNames);
   return filterNames;
}
 
// Check if a condition is true for all types
template <bool...>
struct TBoolPack;
 
template <bool... bs>
using IsTrueForAllImpl_t = typename std::is_same<TBoolPack<bs..., true>, TBoolPack<true, bs...>>;
 
template <bool... Conditions>
struct TEvalAnd {
   static constexpr bool value = IsTrueForAllImpl_t<Conditions...>::value;
};
 
// Check if a class is a specialisation of stl containers templates
// clang-format off
 
template <typename>
struct IsList_t : std::false_type {};
 
template <typename T>
struct IsList_t<std::list<T>> : std::true_type {};
 
template <typename>
struct IsDeque_t : std::false_type {};
 
template <typename T>
struct IsDeque_t<std::deque<T>> : std::true_type {};
// clang-format on
 
} // namespace RDF
} // namespace Internal
 
namespace Detail {
namespace RDF {
 
/// The aliased type is `double` if `T == RInferredType`, `U` if `T == container<U>`, `T` otherwise.
template <typename T>
using MinReturnType_t = typename RDFInternal::RMinReturnType<T>::type;
 
template <typename T>
using MaxReturnType_t = MinReturnType_t<T>;
 
template <typename T>
using SumReturnType_t = MinReturnType_t<T>;
 
} // namespace RDF
} // namespace Detail
} // namespace ROOT
 
/// \endcond
 
#endif